A particulate filter for collecting particulates in exhaust gas emitted from an internal combustion engine has been disclosed in published Japanese translation of PCT-application, JP-T-8-508199. In this particulate filter, a honeycomb structure is formed of porous material and some of a plurality of paths (hereinafter referred to as filter paths) in this honeycomb structure are closed at their upstream ends, while remaining filter paths are closed at their downstream ends. Consequently, exhaust gas flowing into the particulate filter always passes through porous walls (hereinafter referred to as filter partition walls) forming the filter paths and flows out of the particulate filter.
In this particulate filter, since exhaust gas always passes through the filter partition wall and after that, flows out of the particulate filter, its particulate collection rate is higher than the particulate collection rate of a particulate filter in which exhaust gas only passes through the filter paths without passing through the partition walls of the particulate filter.
In the particulate filter disclosed in the above described publication, the filter path is closed by gathering the end portions of the filter partition walls and bonding together these end portions. Consequently, the exhaust gas flow-in opening in the filter path is shaped in a funnel. If the exhaust gas flow-in opening in the filter path is shaped in a funnel, exhaust gas flows into the filter path smoothly without a turbulent flow. That is, no turbulent flow is generated in exhaust gas when exhaust gas flows into the filter path. Thus, pressure loss of the particulate filter disclosed in the publication is low.
In the particulate filter of the above-described type, the filter path is completely closed by gathering the end portions of the filter partition walls such that the end portions are in contact with each other and baking the end portions being in contact with each other so as to bond together the end portions. Consequently, the filter path is completely closed. However, when the end portions that are in contact with each other are baked, these end portions are separated due to an influence of thermal expansion of the end portions and surrounding filter partition walls, so that the filter path may not be completely closed.